From 3c44b75416fb8bc18d946cc0ca14f360be5e702a Mon Sep 17 00:00:00 2001
From: w1n5t0n <w1n5t0n@lnfinitemonkeys.org>
Date: Fri, 3 Apr 2026 18:20:29 +0100
Subject: [PATCH] =?UTF-8?q?fix(playground):=20decouple=20MIDIInput=20from?=
 =?UTF-8?q?=20C15Bridge=20=E2=80=94=20use=20SynthEngine=20interface=20(mem?=
 =?UTF-8?q?l-se4)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 playground/js/a-app.js            |  3 ++-
 playground/js/synth/midi-input.js | 15 +++++++++------
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/playground/js/a-app.js b/playground/js/a-app.js
index 5453317..1db3f47 100644
--- a/playground/js/a-app.js
+++ b/playground/js/a-app.js
@@ -810,6 +810,7 @@ async function setActiveEngine(engine) {
   activeEngine = engine;
   c15 = engine; // keep alias in sync
   arpeggiator.setEngine(engine);
+  if (midiInput) midiInput.setEngine(engine);
   const btn = document.getElementById('synth-mode-btn');
   if (btn) btn.textContent = engine.displayName;
   const engineDockBtn = document.querySelector('[data-drawer="params"]');
@@ -916,7 +917,7 @@ async function init() {
     if (el) el.textContent = msg;
   };
   arpeggiator = new Arpeggiator(activeEngine);
-  midiInput = new MIDIInput(activeEngine.bridge); // MIDIInput still talks to the C15 bridge directly
+  midiInput = new MIDIInput(activeEngine);
   initMIDIControls();
 
   // MIDI Output
diff --git a/playground/js/synth/midi-input.js b/playground/js/synth/midi-input.js
index c441175..dfd0707 100644
--- a/playground/js/synth/midi-input.js
+++ b/playground/js/synth/midi-input.js
@@ -1,9 +1,9 @@
 // MIDI Input — receives notes and CCs from external MIDI controllers
-// Uses Web MIDI API, routes note on/off to C15 bridge
+// Uses Web MIDI API, routes note on/off through a SynthEngine interface
 
 export class MIDIInput {
-  constructor(bridge) {
-    this.bridge = bridge;
+  constructor(engine) {
+    this.engine = engine;
     this.enabled = false;
     this.midiAccess = null;
     this.selectedInputId = null;
@@ -19,6 +19,9 @@ export class MIDIInput {
   set onInputsChange(fn) { this._onInputsChange = fn; }
   set onCC(fn) { this._onCC = fn; }
 
+  /** Hot-swap the engine (e.g. when the user switches synth engines). */
+  setEngine(engine) { this.engine = engine; }
+
   _status(msg) {
     console.log('[MIDI]', msg);
     this._onStatusChange?.(msg);
@@ -130,15 +133,15 @@ export class MIDIInput {
     switch (type) {
       case 0x90: // Note On
         if (data2 > 0) {
-          this.bridge.noteOn(data1, data2 / 127);
+          this.engine.noteOn(data1, data2 / 127);
         } else {
           // Velocity 0 = note off
-          this.bridge.noteOff(data1);
+          this.engine.noteOff(data1);
         }
         break;
 
       case 0x80: // Note Off
-        this.bridge.noteOff(data1);
+        this.engine.noteOff(data1);
         break;
 
       case 0xb0: // Control Change